New waste management design mimics the human respiratory system

August 23, 2007 Amidst the spectacular feats of man-made engineering we regularly encounter, it’s sometimes easy to overlook the subtle sophistication and complexity of biological processes at work in the human body. Hans Fahlenkamp, a chemical engineering professor at the University of Dortmund, has designed a method of separating carbon dioxide from flue gas based on a similar mechanism at work in the human lung. If successful, it will be far more efficient than existing techniques, lessening the environmental impact of power plants and easing the stress on countries that seek to meet tightening emission guidelines.

The flue gas Fahlenkamp’s creation seeks to cleanse is exhaust created from the combustion of fossil fuels in power plants. In a modern large-scale plant with a rating of 1000 megawatts, three million cubic meters of flue gas pass through the chimney every hour. In order to reduce the effect this has on the environment, the flue gas must be subjected to a refinement process before being released. Common techniques used are wet scrubbing, which involves saturating the material with water, dry scrubbing, which uses alkaline to synthesize the waste into crystals, and electrostatic air cleaners, which ionize the offending particles and attract them to plates. However, none of these methods are perfect, and all create residue “silt” which leads to further problems of disposal and pollution. When there are 20 kilos of dust left, it only amounts to one third of the legal limit. But after 1000 operating hours the total can reach 20 tons.

The human lung successfully, and cleanly, processes one kilogram of carbon dioxide per day. While it sounds far removed from the smoke belching plants and factories in terms of size, the method it uses to control the element is sufficiently different to current models that Fahlenkamp believes it can be scaled up with great effect. Fahlenkamp’s design forces the flue gas through a series of tubes, while mixing it with detergent. The carbon dioxide is drawn into the detergent through microscopic pores. This mirrors the natural process that occurs in our bloodstreams every day.

Separating carbon dioxide from flue gas cleanly and efficiently is imperative for reducing emissions. Fahlenkamp’s design serves as a reminder that, while many agree that the future lies in alternative energy, it is also vitally important that we continue striving to improve the current (albeit flawed) system.